relies on tech likes gas chromatography and mass spectrometry, compare samples with patterns of known performance-ehhancing drugs.
so if athletes take something new, it won't be detected.
only very very stupid athletes take steroids now, even the mlb players use new compounds now
blood test for EPO and new method to detect HGH are invented, but i am not sure IOC and WADA do those in beijing olympics or not
it's always called cat-and-mouse fights, IOC and WADA are optimistic that cats are winning, i am not so sure
one thing i am proud is that most chinese strong events are not quite related to PED, except weightlifting
but the problem most those event sdepend on judge, which china has little control, unlike usa and russia.
so expect a sharp decline of medals for china in 2012